Method of controlling pitch in paper using amine coated clays

ABSTRACT

In the manufacture of paper, the deposition of pitch is reduced by adding to the pulp from which paper is to be made a quantity of a clay pigment which has been coated with an organic material which adheres strongly to the clay pigment and which renders the surface of the particles of said clay pigment oleophilic.

United States Patent 1 Windle [4 1 Apr. 2, 1974 METHOD OF CONTROLLING PITCH 1N PAPER USING AMINE COATED CLAYS [75] Inventor: William Windle, St. Austell,

England [73] Assignee: English Clays Lovering Pochin and Company Limited, St. Austell, Cornwall, England [22] Filed: Oct. 12, 1971 [21] Appl. No.: 188,469

[30] Foreign Application Priority Data Oct. 14, 1970 Great Britain r. 48909/70 [52] US. Cl. 162/181 D, 106/308 N, 162/10, 162/D1G. '4

[51] Int. Cl D2lh 3/78 [58] Field of Search 162/10, 181 D, DIG. 4, 162/166, 181 A, 179; 106/308 F, 308 N, 308

[56] References Cited UNITED STATES PATENTS 3,682,696 8/1972 Yasuda 162/181 D OTHER PUBLICATIONS Casey, James P.; Pulp and Paper, Vol. 11, Second Edition, Interscience Publishers Inc., New York, p. 1091, 1096 TS1105 C29.

Rydholm, Sven A., Pulping Process, Interscience Publishers Inc., 1965, NY. p. 1045 TS 1175 R9.

Primary Examiner-S. Leon Bashore Assistant Examiner-William F. Smith Attorney, Agent, or FirmArmstrong & Wegner [57] ABSTRACT 7 Claims, No Drawings METHOD OF CONTROLLING PITCH IN PAPER USING AMINE COATED CLAYS BACKGROUND OF THE INVENTION This invention relates to the manufacture of paper, and more particularly is concerned with a method of controlling the deposition of pitch during the manufacture of paper.

Pitch is the material which can be extracted from wood and mechanical or chemical pulps by means of organic solvents. This material comprises predominantly fatty acids, fatty esters, resin acids and unsaponifiable material such as sterols, waxes and higher alcohols. Both hardwoods and softwoods contain fatty acids, fatty acid esters and unsaponifiable materials, but only softwoods contain significant amounts of resin acids. This latter material occurs in wood mainlyin the ray cells and resin canals or ducts. Softwoods or gymnosperms such as pine or spruce therefore cause more serious pitch problems than hardwoods such as birch, maple, oak and poplar. Pitch may coagulate on almost any piece of pulp and paper equipment, for example wires, felts, press rolls, drier rolls, and the deposits thus J formed result in paper with dark spots, holes or uneven thickness and can retard production rates and even cause tears in the paper. The two most important processes for preparing chemical pulps are the sulphite process in which groundwood is cooked in an acid solution of calcium bisulphite saturated with sulphur dioxide, and the sulphate or Kraft process in which the cooking is performed in an alkaline solution comprising caustic soda, sodium sulphide and sodium hydrosulphide. When pulp is prepared by the sulphate process the pitch problem is much less serious as the cooking solution is alkaline and most of the pitch forming material is removed by saponification.

Hitherto, attempts to reduce the deposition of pitch during the manufacture of paper have involved the addition of certain pitch control agents, such as special grades of talc, asbestos anddiatomaceous earth, to the wood pulp. This has necessitated an additional component being added to the wood pulp.

It is an object of the present invention to provide a method of manufacturing paper in which there is employed a combined filler-pitch control agent which is both cheap and efficient and which obviates the incorporation of a further pitch control agent.

SUMMARY OF THE INVENTION According to the present invention, there is provided in a'method of manufacturing paper, the step of reducing the deposition of pitch during the manufacture of the paper by incorporating into the pulp from which paper is to be made a quantity of a clay pigment which has been coated with an organic material which adheres strongly to the clay pigment and which renders the surface of the particles of said clay pigment oleophilic. I

Advantageously, the strongly adherentorganic material used.-to coat the clay pigment and thereby to render the surface of said pigment oleophilic comprises (a) organic amines containing from 6 to 25 carbon atoms, or water-soluble salts thereof, e.g. their acetates, hydrochlorides or alkyl carbamates, or their reaction. products with alkylene oxides, e.g. propylene oxide or butylene oxide; and (b) alkyl pyridinium salts and quaternary ammonium salts. Organic materials of the above types which can be used to coat a clay pigment in accordance with the present invention include octadecylamine and its acetate; hexadecylamine; amines and amine acetates derived from tallow and hydrogenated tallow; alkyl propylene diamines and diamine diacetates where the alkyl group is derived from tallow; and stearoxymethyl pyridinium chloride.

Generally, the organic material, which can be a single compound or a mixture of such compounds, can be applied to the clay pigment at a dose rate in the range of from 0.5 percent to 5 percent by weight of dry clay pigment.

A method of preparing a coated clay pigment for use in the present invention comprises spraying a jet of the coating compound or compounds which has or have been made liquid into a heated impact mill in which the clay pigment to be coated is being ground.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferably, in a method of preparing a coated pigment in accordance with the present invention, the pigment being ground contains not more than 10 percent by .weight of water. The coated clay pigment which has been ground will, on leaving the impact mill, generally contain not more than 1 percent by weight of water.

The coated clay pigment is preferably added to the pulp in a substantially dry condition, i.e. containing not more than about 1 percent by weight of water. It is also advantageous to add the coated clay pigment to the pulp at the earliest possible stage in the stock preparation process, i.e. at the first beating or refining stage. This allows the mechanical action of the beater or refiner to aid in the dispersion of the pigment evenly throughout the pulp fibres while simultaneously fibrillating the fibres.

The coated clay pigment will generally be added to the wood pulp at a dose rate of not more than 7.5 percent by weight based on the weight of bone dry wood pulp. The preferred dose rate is from 0.8 percent to 2.5 percent by weight of the bone dry wood pulp. Excess coated clay tends to render the wood pulp hydrophobic.

It has been'found advantageous, for metering purposes, to use a coating compound or coating compounds which, when made liquid, is or are slightly electrically conducting. This can be achieved, for example, by using a mixture of an amine and its acetate in. a ratio by weight of 2 to l.

The invention will be illustrated in the following Example.

EXAMPLE A preliminary test was performed on a number of wood pulps in order to find two which gave a high pitch deposit when used under standard conditions in a PFl-mill, i.e. a high-speed laboratory disintegrator mill having a slotted disc-shaped rotor surrounded by with octadecylarrgrg in accordancewith thgir ygntion,

The untreated clay contained 84 percent by weight of particles smaller than 2 microns and 0.06% by weight of particles larger than microns. while the treated clay .contained 47.5% by weight of particles smaller than 2 microns and 29.4% by weight of particles equal to or largerthan 4 microns. The wood pulp was passed through a standard bronze PF I-mill under' the following operating conditions:

1.8 Kgf/cm bar length 6 m/s Pulp quantity (calculated as bone dry): Pulp consistency:

Load:

Relative speed between roll and housing: Distance between roll and housing: Number of revolutions:

TABLE I.TESTS WITH BLEACHED SPRUCE SULPHITE PULP Quantity of pitch Material tested (average of 2 runs) Pulp alone 35 mg Pulp+ 2% untreated clay mg Pulp+ 5% untreated clay 13 mg Pulp+ 2% treated clay 8 mg Pulp+5% treated clay 3 mg TABLE ll.TESTS WITH UNBLEACHED SPRUCE SULPHITE PULP Quantity of pitch Material tested (average of 2 runs) Pulp alone 30 mg Pulp & 2% untreated clay 18 mg Pulp & 5% untreated clay 15 mg. Pulp & 2% treated clay 9 mg Pulp & 5% treated clay The clay pigment used in the foregoing Example was.

kaolinitic clay.

I claim:

1. In a method of manufacturing paper, the step of reducing the deposition of pitch during the manufacture of the paper by incorporating into the pulp from which paper is to be made a quantity of a clay pigment which has been coated with 0.5 to 5 percent based on t ei ht 9 aid. 9 2x ism rttqfaapizan s ma e i which adheres strongly to the clay pigment and which renders the surface of the particles of said clay pigment olephilic, the amount of said clay pigment being not more than 7.5 percent by weight of the bone dry pulp, said organic material being selected from the group consisting of organic amines containing from six to 25 carbon atoms, water-soluble salts of organic amines containing from six to 25 carbon atoms, reaction products of organic amines containing from six to 25 carbon atoms with an alkylene oxide, alkyl pyridinium salts and quaternary ammonium salts.

2. A method according to claim 1, wherein the coated clay pigment is added to the pulp in a substantially dry condition.

3. A method according to claim 1, wherein the coated clay pigment is added to the pulp at the first beating or refining stage.

4. A method according to claim 1, wherein the pulp is formed predominantly from gymnosperms.

5. A method according to claim 1, wherein the pulp is obtained by the sulphite process.

6. A method according to claim 1, wherein the coated clay pigment is added to the wood pulp at a dose rate of from 0.8 percent to 2.5 percent by weight of bone dry wood pulp.

7. Paper including a filler which comprises a clay pigment which has been coated with 0.5 to 5 percent based on the weight of said clay pigment of an organic material which adheres strongly to the clay pigment and which renders the surface of the particles of said clay pigment oleophilic, the amount of said clay pigment being not more than 7.5 percent by weight of the bone dry pulp and used to make said paper, said organic material being selected from the group consisting of organic amines containing from six to 25 carbon atoms, water-soluble salts of organic amines containing from six to 25 carbon atoms, reaction products of organic amines containing from six to 25 carbon atoms with an alkylene oxide, alkyl pyridinium salts and quaternary ammonium salts. 

2. A method according to claim 1, wherein the coated clay pigment is added to the pulp in a substantially dry condition.
 3. A method according to claim 1, wherein the coated clay pigment is added to the pulp at the first beating or refining stage.
 4. A method according to claim 1, wherein the pulp is formed predominantly from gymnosperms.
 5. A method according to claim 1, wherein the pulp is obtained by the sulphite process.
 6. A method according to claim 1, wherein the coated clay pigment is added to the wood pulp at a dose rate of from 0.8 percent to 2.5 percent by weight of bone dry wood pulp.
 7. Paper including a filler which comprises a clay pigment which has been coated with 0.5 to 5 percent based on the weight of said clay pigment of an organic material which adheres strongly to the clay pigment and which renders the surface of the particles of said clay pigment oleophilic, the amount of said clay pigment being not more than 7.5 percent by weight of the bone dry pulp and used to make said paper, said organic material being selected from the group consisting of organic amines containing from six to 25 carbon atoms, water-soluble salts of organic amines containing from six to 25 carbon atoms, reaction products of organic amines containing from six to 25 carbon atoms with an alkylene oxide, alkyl pyridinium salts and quaternary ammonium salts. 